N-(2-acetyl-4,6-dimethylphenyl)-3-{[(3,4 dimethyl-5-isoxazolyl)amino]sulfonyl}-2-thiophenecarboxamide is an endothelin antagonist (U.S. Pat. No. 6,686,382). Endothelin antagonists are useful for the treatment of hypertension such as peripheral circulatory failure, heart disease such as angina pectoris, cardiomyopathy, arteriosclerosis, myocardial infarction, pulmonary hypertension, vasospasm, vascular restenosis, Raynaud's disease, cerebral stroke such as cerebral arterial spasm, cerebral ischemia, late phase cerebral spasm after subarachnoid hemorrhage, asthma, bronchoconstriction, renal failure, particularly post-ischemic renal failure, cyclosporine nephrotoxicity such as acute renal failure, colitis, as well as other inflammatory diseases, endotoxic shock caused by or associated with endothelin, and other diseases in which endothelin has been implicated. Provided herein are processes for the preparation of N-(2-acetyl-4,6-dimethylphenyl)-3-{[(3,4 dimethyl-5-isoxazolyl)amino]sulfonyl}-2-thiophenecarboxamide.